1. Field of the Invention
The preset invention relates to an arrangement unit for an umbilical member arranged at a robot wrist section of an industrial robot.
2. Description of the Related Art
When an industrial robot is used, the robot is required to be provided with an umbilical member including a cable for transmitting power or a signal and/or a tube for transmitting coolant or activation gas to an end effector, such as a hand or a welding gun, attached to the end of a wrist section of the robot, via a forearm of the robot. It is necessary that the umbilical member, arranged around the wrist section of the robot, has a certain amount of extra length (margin) so that excess force is not applied to the umbilical member over the entire operation range of the wrist section. On the other hand, the extra length of the umbilical member may be slack depending on the position and/or the orientation of the wrist section of the robot, and the umbilical is required to not interfere with external equipment, such as a neighboring robot, a hand, a jig, workpiece, etc.
For example, Japanese Unexamined Patent Publication No. 2003-136462 discloses an intermediate member for avoiding interference with a cable or the like and external equipment. Concretely, it is described that intermediate member 6 is disposed between a wrist flange 4 and a spot welding gun 5, and has connecting members 6c and 6d parallel to each other. In this regard, a welding cable 7 extends below intermediate member 6 and is fixed to spot welding gun 5 via the center of a third wrist axis 23 and a region between connecting members 6c and 6d. 
Further, Japanese Unexamined Patent Publication No. 2005-288560 discloses an intermediate member or a connecting member for avoiding interference between a tube/wire member and external equipment. Concretely, it is described that C-shaped connecting member 7 has a connecting wall 71 arranged at one circumferential side and guide members 73, 73 arranged at an opening 72 at a side opposed to connecting wall 71.
In the configuration of Japanese Unexamined Patent Publication No. 2003-136462, when the umbilical member is replaced with another, removing and attaching of the umbilical member relative to the intermediate member must be carried out, which is troublesome for an operator and maintenance performance may be decreased. On the other hand, in the configuration of Japanese Unexamined Patent Publication No. 2005-288560, the umbilical member may protrude from the opening and interfere with external equipment. Further, since the rigidity of the connecting member at the opening is relatively low, the end effector easily vibrates during operation of the robot. One way to avoid the vibration of the end effector is to limit the operation speed of the robot. However, a cycle time of the operation is increased in this case.